Need to catch up on what’s been going on in the world of motorcycling over the last week? Here’s your five-minute briefing.

1: Aprilia RS660 spied on test

Of all the bikes at the EICMA show in Milan last month Aprilia’s RS660 concept was perhaps the most intriguing – appearing to herald a return to form for a middleweight sports bike scene that’s been in decline for years.

At the show it was just a concept, so we were cautious about getting too excited, but now at least two prototype examples of the RS660 have been spotted on test at the Vallelunga circuit near Rome, with one looking very close to production-ready.

Aprilia didn’t give away many details about the RS660 concept at EICMA. It’s a parallel twin with an engine that’s basically the front two cylinders from the firm’s RSV4 superbike’s V4 engine. The ‘RS660’ name suggests it’s been stretched to 660cc, probably via a longer stroke – the same trick that Norton has used to develop its new 650cc parallel twin from a 1200cc V4.

Similarly Aprilia has made no claims about power, although as an engine that’s derived from a 200bhp-plus superbike V4, we’d hope the 660 twin can achieve something north of 100bhp. Norton’s Superlight claims 105bhp from its 650cc engine, and is surely the RS660’s closest rival. Hopefully the Aprilia will be much cheaper than the £20k Norton, though.

Aprilia’s new parallel twin engine is expected to form the basis of an entire range of bikes, so the RS660 sports model is just the start. Eventually we can expect a middleweight naked ‘Tuono’ version as well, and an adventure-style machine is also likely.

Low weight is likely to be a key element of the bike’s appeal. By using a minimalist, half-length frame and relying on the engine and transmission to provide much of the structure, the RS660 promises to be much lighter than more powerful four-cylinder 600-class rivals.

With one of the machines spotted on test already sporting a licence plate bracket, lights, mirrors and indicators, it looks like the prototypes are already in the road-testing phase of development. That suggests they’re not too far from production readiness, and could join the Aprilia range as soon as 2020.

2: Ducati goes dry clutch

When the bike was revealed at EICMA last month, a wet clutch was evident and the spec sheet confirmed it, saying the bike would be fitted with a “hydraulically controlled slipper and self-servo wet multiplate clutch.”

Our man Jon Urry even asked the V4 R’s project leader, Stefano Strappazzon, about the decision to move away from the dry clutches that have long defined range-topping Ducati superbikes. He said: “We could have homologated one for the V4 R road bike, and the race team are testing a dry alongside a wet clutch, but we decided not to use it as it was no better than the standard wet clutch.”

However, there’s been an about-face at Ducati, and now the V4 R will come with a dry clutch after all. The latest iteration of the V4 R’s spec sheet says there’s a “hydraulically controlled slipper and self-servo dry multiplate clutch” and the revised press kit includes a whole section singing the praises of the dry clutch:

As in MotoGP, where all that matters is maximum performance, the Panigale V4 R features a dry clutch. The V4 R mounts an STM EVO-SBK clutch, made of machined-from-solid aluminium with a 48-tooth clutch basket and plate set; there are 9 take-up plates and 9 drive plates with a diameter of 138 mm.

During extreme on-track use, this gives greatly improved ride 'feel'. More specifically, the dry clutch ensures a more efficient anti-patter function, even during aggressive downshifting, and greater fluidity during 'off-throttle' phases; moreover, it's also possible to personalise the degree of 'mechanical' engine braking by selecting a different secondary spring from those available in the Ducati Performance accessories catalogue.

Further benefits include the absence of the resistance opposed by the engine oil and reduced oil contamination as dust from disc wear is not carried into the lubrication circuit.

Last but not least, there's the iconic mechanical clutch rumble which Ducati fans find irresistible.

3: Is this BMW’s 1800cc cruiser engine?

This big boxer custom bike was named ‘best in show’ at this week’s Hot Rod Custom Show in Yokohama, Japan, but it really stands out because the engine – an boxer twin with pushrod valve operation – is an official BMW-made prototype.

That motor is reported to have been delivered to Japanese custom builders Custom Works Zon in July under a veil of secrecy. Details of its design remain unknown, although the bike’s name – R18 – could be a suggestion that it’s an 1800cc motor. Or perhaps it’s just because it’s made in 2018…

Pushrod tubes are clear to be seen, and the design is clearly reminiscent of early BMW boxers. Although it’s worth pointing out elements like the machined rocker covers are custom parts made by Zon, not components provided by BMW.

BMW has long been rumoured to be developing a large-capacity boxer engine that will form the basis of a return to the cruiser scene for the first time since the R1200C was discontinued back in 2004. This motor certainly looks the part, and since BMW has a track record of testing the waters with custom bikes made by external collaborators – like the original Roland Sands-designed Concept 90 that previewed the R NineT – it’s quite possible that the firm is preparing the ground for its entry into the Harley-dominated cruiser market by illustrating just how well its new design can be adapted into one-off customs.

Remember that in 2016 BMW showed its own cruiser custom concept – the R5 Hommage. That machine had a newly-designed frame and styling but used a real pre-war BMW boxer twin. Is the firm’s plan to combine the R5 Hommage’s style with the new engine seen in the Custom Works Zon R18? It would make a lot of sense.

4: Rotobox Splice

Remember the brief supermoto craze from a few years ago? It led to bikes including Ducati’s Hypermotard, but quickly receded back to the smaller subculture that it had previously been. But supermotos are still a thing.

This one – the Rotobox Splice – comes from a Slovenian firm that actually specialises in lightweight carbon-fibre wheels, and it’s about as exotic as a supermoto can get.

With a list price of €29,830 (£26,545) – excluding VAT, which would take it to £31,854 in this country, not including the price of importing and registering it – it’s clearly aimed at those with particularly fat wallets.

The name ‘Splice’ is a reflection of what the firm does to create the bike. It starts with a 2018 or 2019 Yamaha YZ250F, YZ450F, WR250F or WR450F (depending on the customer’s preference) and then modifies it to accept the swingarm from a Yamaha R6, allowing the firm to fit a wide, 190-section rear tyre.

Of course, that’s just the start. The final machine is dripping with carbon fibre, including carbon wheels of course, which helps make it remarkably light. The firm claims that the kerb weight, including a full tank of fuel, is just 119kg. It’s also got the usual mix of top-end Brembo and Ohlins kit to further justify that astounding price tag.

5: BMW R1250GS picks up where the R1200GS left off

The introduction of a new model normally leads to a decline in sales for its predecessor – but BMW has pulled off spectacular transition with the launch of its R1250GS.

The firm managed to get the new bikes into dealers almost as soon as it was announced, and as such there was little slackening of R1200GS sales before the R1250GS took its place.

The success of the switchover is clearly illustrated by newly-released sales figures for the German bike market in October – the month of the R1250GS’s launch.

Incredibly, the R1200GS and R1250GS occupy the number one and number two spots in Germany’s sales charts for October, with the older bike just edging is successor with 224 sales compared to 219. The next-best-selling model that month was the Kawasaki Z650 on a mere 137 sales.

While we don’t get such detailed breakdowns of British sales, we know that in October the best-selling machine over here was the Honda Africa Twin, with 279 registered during that month. The new R1250GS achieved 129 UK registrations in the same period, outselling the older model.

Italian figures also show how BMW’s adventure bike went from strength to strength, with October sales revealing that 170 of the older R1200GS machines were sold alongside 158 of the new R1250GS models.